Like her father and brother, Rooney Mara prefers her middle name to her first, even if it does link her even more closely to her football heritage. (Her great-grandfathers, Timothy Mara and Art Rooney Sr., founded the New York Giants and Pittsburgh Steelers, respectively.) But the star of “The Girl With the Dragon Tattoo” doesn’t mind the connection. According to her, it’s better than being called by her given first name, Patricia.

Mara plays Lisbeth Salander, the antisocial black-clad computer-hacking protagonist in the David Fincher-directed film based on the best-selling book by Swedish author Stieg Larsson. Speakeasy sat down with a black-clad Mara at the Crosby Street Hotel to discuss her choice to stay away from social media and football and her desire for a strong-willed director.

The Wall Street Journal: Why have you chosen to go by your middle name?

I just liked it better. My dad and my little brother both go by their middle names, it didn’t feel that strange to me. Unfortunately it didn’t disassociate me from football but I think it’s a really cool name and I never really liked my first name, Patricia. A lot of people in my family go by their middle name so it was the natural course.

The film is done. Why did you decide to to keep Salander’s jet-black hair?

I’m keeping the hair color purely because it’s really damaging to dye your hair lighter. I don’t want to dye it lighter and then get a job and they want to dye it darker, so I’m just waiting to get a job and they can tell me what they want to do with it.

You’ve now worked with David Fincher on two films back-to-back–”The Social Network,” and now “Dragon Tattoo.” Will it be difficult to have another person direct you?

I think working with David has made me much more hungry and aware of directors who have a very specific process. It doesn’t have to be the same process as his but I really appreciate working with people who know what they want and know how to get it. I like working with people who are uncompromising in their process and in their storytelling but it doesn’t have to be someone who works in the way that David works.

Because Salander is such an intense character, how did you separate yourself once the cameras were off?

I don’t really have an active process, not something I actively think about. Certainly with a character like this when you have to go through a physical transformation its harder to separate yourself from that character because you are living looking like them. But at the same time when we were shooting in Los Angeles we were shooting 14-16 hours a day six days a week, so you don’t really think about that. You go home and go to sleep and do it again the next day. There isn’t much time to think about getting off of it.

Once you finished shooting, was it difficult to come out of character?

We never really finished the movie. We finished and I knew we had re-shoots so there wasn’t a clear ending to it. I had to hold onto it for a little bit longer which was definitely hard. We weren’t working but I had to stay in character and I was not allowed to do anything to the look and I think it’s hard in general to come off of an experience that was over a year of my life working at 100 miles per hour. It’s hard to wake up and have nothing to do one day, it’s a hard transition.

You’ve make a conscious choice to stay away from social media like Twitter. Why?

I think people don’t really know anything about me and I think it’s probably better that way. I think that’s why David Fincher cast someone like me. He didn’t cast someone that the audience has a relationship with because it makes it much easier to get lost in this movie and believe me in this character, the less you know about me. I think it is sort of a strange part of our culture that’s growing. It’s a misconception. I don’t think audiences need to know anything about me. I think it’s a distraction to the work, certainly for a character like this who is such an enigma. She has to be a question mark. If people are watching the movie thinking about football or why I didn’t become a football player or why I’m not working for the Giants, that wouldn’t be a very good thing.

For more coverage on “The Girl With the Dragon Tattoo” and other films, follow Alexandra Cheney on Twitter @alexandracheney.

About Speakeasy

Speakeasy is a blog covering media, entertainment, celebrity and the arts. The publication is produced by Barbara Chai and Jonathan Welsh with contributions from the Wall Street Journal staff and others. Write to us at speakeasy@wsj.com or follow us on Twitter at @WSJSpeakeasy or individually @barbarachai.